Leftover brewing grains have been fed to livestock since the dawn of agriculture, so this is a pretty radical shift. The proposed new requirements for animal feed handling stipulate that the feed has to be dried, analyzed and packaged before being donated to farmers (the spent grains are generally given away at the end of the brewing process), at substantial expense.

It's clear that food safety is important, but I'm not convinced that the stringency of this rule is commensurate with the risk.

Brandon Mazer is legal counsel for Maine’s largest brewer, Shipyard, which produces 400-600 tons of spent grain per week during its peak production seasons. Those grains are dumped onto a truck trailer and go to farms as feed.

“It’s a very big umbrella, and we got sucked under it,” Mazer said of the proposed FDA rule change. He said that no brewers in Maine, and few in the country, are equipped with the machinery, personnel or money to meet the requirements outlined by the FDA.

The Brewers Association, Beer Institute, American Malting Barley Association and other brewing organizations have voiced strong opposition to the new restrictions, calling for an exemption for brewers.

The Beer Institute says that in 2012 alone, U.S. brewers produced about 2.7 million tons of spent grain.

The FDA has extended the public comment period on this set of rules until March 31, and brewers and farmers that work with them say they are watching closely.